The present invention relates to object-detection devices. It is particularly concerned with ultrasonic devices used on automobiles.
The pursuit of highway safety has led to numerous proposals for devices to be used in automobiles to detect the proximity of other vehicles. Some of these devices are used to detect the presence of a vehicle in front of the car, thereby detecting an impending crash and causing the brakes to be applied automatically. Others have been directed to the detection of vehicles in "blind spots" so that the driver can be warned not to turn into the path of an oncoming vehicle.
The use of ultrasound for object detection has been proposed for both types of devices, and ultrasound has been proved effective as a means for detecting objects. However, in contrast to those systems in which detection of an object automatically results in, say, application of the car's brakes, those systems in which the driver of the car is to be alerted must do more than merely detect the other vehicles accurately. Such systems must additionally operate effectively as information systems, presenting information to the driver in such a way that he can use it effectively.
It is accordingly an object of the present invention to notify the driver of the presence of vehicles in his "blind spot" only at those times when he is most likely to need such information. Another object is to present the information in such a manner that the driver can easily confirm the operability of the system and can thereby rely on the system with confidence. A further object is to enable the use of numerous ultrasonic frequencies even at high automobile speeds.